This application is a 371 application of PCT/EP00/05872, filed Jun. 23, 2000.
The invention relates to a machine for chopping organic cut products, especially a meat grinder, comprising an inlet and an outlet for the cut products, at least one perforated disc having a corresponding cutting head and a drive shaft driving the cutting head, the cutting head having at least one blade holder with at least one blade that cooperates with the perforated disc.
Machines for chopping organic cut products, especially meat grinders, are known from prior art, e.g. from WO 98/28076 wherein a grinder having an adjustable cutting means is described. In this generic printed document, the cutting head is mounted on the drive shaft so as to be axially displaceable, yet non-rotatable.
As a result of such mounting, the blade holder can be pressed by a spring against the cooperating perforated disc and re-adjusted as the cutting members undergo wear. In this way, wear of the blade or perforated disc is compensated automatically. Blade/perforated disc systems of this type function according to the principle of shearing, i.e., the cutting edges of the blades and of the perforated discs must be in permanent contact in order to be capable of chopping the cut products (in particular, tough components such as tendons in meat) with the desired high quality.
In the processing of many products, even not more than a brief interruption of contact between the cutting edges will give rise to jamming of the perforated disc, so that the machine has to be cleaned and thus, the production interrupted.
Primarily, permanent contact of the cutting edges is opposed by process-immanent wear, necessitating the spacing between the cutting edges to be corrected again and again. Furthermore, in case the cutting members are to comply with the function of conveying in addition to that of cutting, restoring forces preventing permanent contact may occur. Depending on the product, such forces may vary widely and have to be eliminated reliably.
In order to ensure contact nonetheless, various constructions have been developed in the past. Therein, either the blade or the perforated disc is displaced axially with respect to the drive shaft, thereby re-adjusting the respective counterpart. For example, such re-adjusting is effected by manual intervention by the operator, by means of prestressed spring(s) WO 98/28076, by means of hydraulic, pneumatic, motor-driven (DE 39 15 409 A1) adjusting systems, or even by utilizing the pressure exerted by the product (DE 44 37 144 A1).
While elastic (e.g. spring-loaded) solutions offer the advantage of automatic re-adjustment, they suffer from the drawback of being sensitive to restoring forces. In contrast, mechanical adjustment systems are insensitive to restoring forces, but disadvantageous in the above-mentioned cutting edge re-adjustment.
One concern in the past has been to develop and elastic system wherein the restoring forces resulting from the conveying effect would not adversely affect the shearing effect, but rather, the blades would make optimum contact with the perforated discs at all times, regardless of any operating condition. The WO 98/28076 has solved this problem by assigning the processes of conveying and cutting to different components and having the restoring forces act on the conveying elements supported on the drive shaft instead of having them act on the spring-loaded blade holders.
However, another problem of such blade/perforated disc systems is that the outer portions of the blades during their rotational movement travel a longer distance than the inner ones and therefore, the inner and outer portions of the blades undergo wear to a different extent, such wear being stronger in the outer portions, in particular. To avoid gaps thus forming between the outer portions of the blades and the perforated disc, the inner portions of the blades would have to undergo an additional and in itself unnecessary wear so as to have contact between all the portions of the blades and the perforated disc.
The invention therefore is based on the object of ensuring optimum contact between the blades and the perforated disc, particularly contact of the blades across the entire range of the cutting edge so as to achieve high quality of the final product.
Said object is accomplished in that the blade is displaceable at an angle relative to the perforated disc plane and is mounted rotatably on the blade holder, that one cutting edge of the blade is parallel to the perforated disc, and that the blade is pressed against the perforated disc by means of an elastic member.
To avoid additional and in itself unnecessary wear of the lower portion of the blades, it is a feature of the invention to hold the blades in the blade holder in such a way that the blades rotate about the axis of their holder and thus, despite uneven wear, are capable of continuously readapting to the perforated disc. This not only stabilizes the product quality, but also reduces wear of the cutting elements as a whole, thereby increasing the service life and the working safety of the machine per set of tools.
If the machine is a meat grinder, the worm conveyor thereof advantageously serves as blade holder at the same time.
According to the invention, the axis about which the blade can be rotated may extend through the blade itself. Conveniently, the cutting head has at least one blade holder with one blade each.
According to the invention, the blades can be pressed against the perforated disc by means of one or more elastic members per blade. However, the blades can also be pressed against the perforated disc by means of one or more common elastic members.
According to the invention, multiple cutting head/perforated disc combinations can be included in one single machine for chopping organic cut products. In this way, a finer division of the cut products can be achieved, because the cut products are coarsely reduced in size in a first stage, while the cut products are finely comminuted in each further cutting stage.
According to the invention, the blades in the cutting head are replaceable, and the drive shaft can be driven by a motor. Advantageously, the elastic members are springs.